Agitator sub

ABSTRACT

A hydraulically driven agitator sub includes: a tubular body for connection within a string including a first mandrel and a second mandrel, and a central bore defining a longitudinal axis of the tubular body and creating a flow path permitting a flow of fluids between the two mandrels and through the tubular body, the second mandrel secured, at least partially, within an annular bore of the first mandrel so that the second mandrel is telescopically arranged with and axially moveable within the first mandrel between a telescopically extended position and a compressed position; and a first sealing part and a second sealing part, one of the first and the second sealing part being secured to the first mandrel and the other sealing part being secured to the second mandrel, both sealing parts being within the fluid flow path of the tubular body, the first sealing part and the second sealing part being positioned to come together when the first mandrel and the second mandrel are in the compressed position to form a seal in the fluid path, the seal substantially preventing the flow of fluids through the tubular body

FIELD

The present invention relates to an apparatus and method for creating anagitation effect in a string.

BACKGROUND

Agitators are employed to facilitate wellbore drilling and installationof wellbore liners. Agitators create a regular movement of the stringthat enhances advancement of the drill bit and prevents slip stick in awell string such as a liner.

SUMMARY

In accordance with a broad aspect of the present invention there isprovided an apparatus comprising: a tubular body for connection within astring including a first mandrel and a second mandrel, and a centralbore defining a longitudinal axis of the tubular body and creating aflow path permitting a flow of fluids between the two mandrels andthrough the tubular body, the second mandrel secured, at leastpartially, within an annular bore of the first mandrel so that thesecond mandrel is telescopically arranged with and axially moveablewithin the first mandrel between a telescopically extended position anda compressed position; and a first sealing part and a second sealingpart, one of the first and the second sealing part being secured to thefirst mandrel and the other sealing part being secured to the secondmandrel, both sealing parts being within the fluid flow path of thetubular body, the first sealing part and the second sealing part beingpositioned to come together when the first mandrel and the secondmandrel are in a fully compressed position to form a seal in the fluidflow path, the seal preventing the flow of fluids through the tubularbody.

In accordance with another broad aspect of the present invention thereis provided a drill string comprising: a string of tubulars; a drill bitconnected at a distal end of the string of tubulars; a drill collar; anda hydraulically driven agitator positioned between the drill bit and thedrill collar.

In accordance with another broad aspect of the present invention thereis provided a method for creating an agitation effect in a wellstring,the method comprising: connecting an apparatus as above in-line with awellbore string to position the second mandrel and the first mandrel inthe compressed position when there is weight on bit in the wellborestring; applying weight on bit to position the first mandrel and thesecond mandrel in the fully compressed position; pumping fluids throughthe wellbore string to develop a fluid pressure overcoming the weight onbit holding the first mandrel and the second mandrel in compressedposition and driving the first mandrel and the second mandrel apart;allowing the pressure to dissipate such that the first mandrel and thesecond mandrel return back to the compressed position; and continuing topump fluids through the wellbore string to create an agitation effect asthe first mandrel and the second mandrel continue to be pumped apart andthen returned to the compressed position.

It is to be understood that other aspects of the present invention willbecome readily apparent to those skilled in the art from the followingdetailed description, wherein various embodiments of the invention areshown and described by way of illustration. As will be realized, theinvention is capable for other and different embodiments and its severaldetails are capable of modification in various other respects, allwithout departing from the spirit and scope of the present invention.Accordingly the drawings and detailed description are to be regarded asillustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings, several aspects of the present invention areillustrated by way of example, and not by way of limitation, in detailin the Figures, wherein:

FIG. 1 is a schematic representation of a typical well bore drillingscenario with one embodiment of the apparatus connected in-line with astring.

FIG. 2A is a side elevation, sectional view of one embodiment of theapparatus in an extended position.

FIG. 2B is a side elevation, sectional view of one embodiment of theapparatus in a sealing position.

DESCRIPTION OF VARIOUS EMBODIMENTS

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various embodiments of thepresent invention and is not intended to represent the only embodimentscontemplated by the inventor. The detailed description includes specificdetails for the purpose of providing a comprehensive understanding ofthe present invention. However, it will be apparent to those skilled inthe art that the present invention may be practiced without thesespecific details.

For the sake of clarity, within this description, the terms “up”,“uphole”, “upper”, “above” generally refer to the direction within thewellbore towards the surface. Likewise, the terms “down”, “downhole”,“lower”, “below” make reference to the direction within the wellboreaway from surface. The terms “inner” and “inward” refer to the directiontowards the center of a wellbore, whereas the terms “outer” and“outward” refer to the direction away from the center of a wellbore, forexample towards the well bore wall. As those skilled in the art of wellbore drilling can appreciate these terms are similarly relevant todeviated and directionally drilled well bores and the tools usedtherein.

The apparatus is an agitator that can be employed to agitate a wellborestring. The string can be a drill string, as shown, or another stringthat requires agitator, such as a liner string. As such, while thefollowing description implies a drilling application, the method andapparatus are equally useful for liner placement applications and anyother application in which a wellbore string requires agitation.

A typical drilling rig 10 is shown on the surface 12 with a well bore 14being drilled through subterranean formations 16 towards a targetreservoir 18, as shown in FIG. 1. Within the wellbore, a string 20 isdepicted including a drill bit 22 and a tubular body 24 is shownincorporated with the string. Drilling rig 10 or a downhole motor (notshown) or any other method known in the art may provide the torsionalforce on the drill bit. The string may include any number and variety ofdownhole elements 27 such as tools, string subs includingmeasurement-while-drilling tools, drill collars, sensors and the like.

The present invention provides an apparatus and method that allows theoperator of a drilling operation to agitate the string in a regular wayduring pumping of fluid through the string and when there is weight onbit. The apparatus may telescopically compress in response to weight onthe string and the apparatus may be used to pump the parts apart untilthey are stopped or the pressure dissipates and weight urges them backtogether causing a hammering effect each time the apparatus recompressedafter being pumped apart.

Because the hydraulic design is capable of generating significantpressures, the agitator can lift a lot of weight. It can, therefore, beplaced close to the bit to have a very direct hammering effect thereon.For example, the agitotaor can be placed between the bit 22 and thedrill collars 27 b, such as the non-magnetic drill collars in adirectional system. Drill collars, and in particular non-magnetic drillcollars, are often called “monels”.

For example, with reference to FIGS. 2A and 2B, the present inventionmay provide an apparatus. The apparatus may comprise a tubular body 24for connection within a string 20 including a first mandrel 28 and asecond mandrel 30. In this embodiment, the first mandrel is depicted aspositioned uphole from the second mandrel.

The tubular body may also include a central bore 26 a, 26 b defining thelongitudinal axis of the body and permitting the flow of fluids, forexample drilling mud, through the tubular body from its upper end to itslower end. The body may include the first mandrel and the second mandrelwith the central bore extending through both mandrels. The first mandrelmay include an outer wall 32 and an inner wall 34.

Central bore 26 a, 26 b may provide a conduit so that, if the apparatusis connected into the string, the central bore becomes continuous withthe bore of the string. This may be of interest for the pumping ofdrilling fluids from the surface through the string and the body to adrill bit. The second mandrel may include an outer wall 54 and an innerwall 56, the later which defines the central bore 26 b through thesecond mandrel. In one embodiment, first mandrel 28 may include an innersleeve 42 that forms an extension through which extends portion 26 a ofthe central bore. Inner sleeve 42 extends generally coaxially with, andspaced from, inner wall 34. An annular hollow chamber 36 is formedbetween sleeve 42 and wall 34. Inner sleeve 42 defines an inner limit ofchamber 36, such that chamber 36 is defined as an annular space definedbetween wall 34 and sleeve 42. The upper end of annular chamber 36 iswall 48 and the lower end of the annular chamber is open.

The second mandrel may be secured, at least partially, within an annularhollow chamber 36 also defined by inner wall 34 of the first mandrel.Second mandrel 30 is telescopically arranged with, and axially moveable,within the first mandrel. The first mandrel and the second mandrel aretelescopically arranged and moveable between an axially compressedposition FIG. 2B and an axially expanded position FIG. 2A. In thesepositions, the madrels remain connected. A first sealing part 52 and asecond sealing part 58 may form part of the apparatus with one sealingpart secured to the first mandrel and the other sealing part secured tothe second mandrel and both sealing parts are, at least partially,within the fluid flow of the tubular body. The first sealing part andthe second sealing part may be positioned to come together when themandrels are compressed, as by applying weight on the string in whichthe apparatus is installed. When the sealing parts come together theymay form a fluid seal in the central bore to substantially prevent theflow of fluids through the tubular body.

First mandrel 28 may include an inwardly directed ledge 50 on its lowerend. Ledge 50 is a return that reduces the inner diameter across chamber36.

The uphole end of the first mandrel may be connectable into the stringthrough a tubular connection 41 a, for example a threaded box or pinarrangement or any other tubular connection.

The inner sleeve may include first sealing part 52 on its inner diametersuch that first sealing part is positioned in the central bore. Forexample, the first sealing part may form an annular surface or a seatwith a central aperture 53. The first sealing part may extend intocentral bore to such an extent that fluid flow is substantially notrestricted through the central aperture. In an alternate embodiment,first sealing part may extend across central bore and have ports, ratherthan a central aperture, therethrough to permit the substantiallyunrestricted fluid flow past first sealing part.

Having described the various embodiments of the elements associated withthe first mandrel, the description now turns to the second mandrel, withone embodiment thereof depicted in Figures 2A and 2B. The second mandrelmay connect into the string, for example to the drill bit via a tubularconnection 41 b such as box or pin threading, etc.

The second mandrel may insert into the first mandrel and have a limitedrange of telescopic movement therein. For example, the second mandrelmay be inserted in annular chamber 36 with at least a portion of outerwall 54 axially slidable along wall 34 and inner wall 56 facing theouter surface of inner sleeve 42.

Extending inwardly from the inner wall and into central bore 26 b may besecond sealing part 58. The second sealing part may include a profileportion 60, which can engage and create a fluidic seal with firstsealing part 52 of the first mandrel. In general, the second sealingpart may be a variety of relevant shapes such as a dart, a ball point,conical, frustoconical, pyramidal and the like that can plug the centeraperture 53 of the first part. For example, the profile portion ofsecond part 58 can seat into and seal against the edges of the centeraperture exposed on first sealing part 52.

Regardless of the specific shape, the second sealing part may haveadjacent thereto one or more flow ports 62 to permit the flow ofdrilling fluid to pass and access the central bore of the stringdownhole of the second mandrel (see flow direction represented by linesX in FIG. 2A). The flow ports can be any shape or size to permit suchflow of drilling fluid. As will be discussed further below, the flowports may be positioned so that if the matching profile portion engagesthe first sealing part drilling fluids cannot flow past the firstsealing part to access the central bore there below. Further, thesealing parts are positioned on their respective mandrels such that thesealing parts come together when the mandrels are fully, telescopicallycompressed.

In an alternative embodiment, where it is not desirable to create aperfect seal in the apparatus second sealing part 58 may also have oneor more apertures 63 or the first sealing part may have apertures, topermit the communication of a small flow of fluids across the secondsealing part even when the first sealing part and the second sealingpart come together. Apertures 63 may permit fluidic communication thereacross so that drilling fluids may have a restricted flow, arrows x1,past the second sealing part even if matching profile 60 is sealed inthe first sealing part. As such, although sealing of the parts iscontemplated to form a pressure pulse sufficient to drive movement andoperation of the tool, such a seal may not be a perfect seal so thatdrilling fluid circulation is not cut off completely.

In one embodiment, the uphole end of second mandrel 30 may include aflange 64 that extends outward therefrom. The flange may, for example,be integral such as a lateral extension of the second mandrel or anadditional component secured to the second mandrel such as a safetyclip. The flange may extend, at least partially, radially out beyondledge 50. The engagement of flange 64 with ledge 50 may define the mostaxially extended position of the limited range of telescopic movementbetween the first mandrel and second mandrel 30, as shown in FIG. 2A.

The apparatus may further include a biasing member 38, if desired, thatbiases the two mandrels into a partially compressed position because thebiasing member has a biasing strength. The biasing member limits theextent to which the parts may be telescopically pulled apart andtherefore determines the stroke length. The biasing member may also actas a shock absorber. As will be appreciated, therefore, the biasingmember may be omitted if neither stroke length determination or shockabsorption are of interest.

Biasing member 38 may act between the first mandrel and second mandrel30 to bias them into a partially compressed position. If the biasingmember is disposed in the annular hollow chamber between the flange 64and the ledge 50, in the most axially extended position, biasing member38 is fully compressed between the ledge and the flange, as shown inFIG. 2A.

Biasing member 38 may be any conventional biasing member such as, forexample, a compression spring. As a further example, compression springsmay be Belleville springs, coiled compression springs, helical springs,variable pitch conical springs and the like. A coiled compression springmay have a known, constant biasing strength that allows the spring toresist applied compressive forces to a predictable degree. If thecompressive forces exceed the biasing strength constant limit, thespring will compress. As will be described further below, the biasingmember acts between the two mandrels to bias them into a partiallycompressed position and in particular, to resist axial movement of thesealing members 53, 60 apart beyond a certain limit. This preventsdamaging forces by the two mandrels being forcibly urged apart, oncepressure builds up above the sealing members.

The biasing member may be selected, when in a neutral position, to leavesome space between the sealing members 53, 60 in order to allow theagitator to be stopped by removing the weight from the string. Inparticular, by lifting the string off the bottom, the second mandrel maydrop by gravity or pump pressure apart such that sealing members do notcome together and cannot cause vibration in the string.

The outer surface of inner sleeve 42 may have an annular gland 66 tohouse an inner sealing member 68. The annular gland may be a roundedgroove, a square cut groove, an indentation etc. In the illustratedembodiment of FIGS. 2A and 2B, annular gland 66 is square cut. The innersealing member may be an o-shaped sealing ring that protrudes from theannular gland so that the sealing member may be compressed betweenannular gland 66 and the inner surface of the second mandrel creatingtherebetween a pressure and fluid seal to prevent fluidic communicationbetween the central bore and the annular hollow chamber. It is to beunderstood herein that the term “sealing member” will, unless otherwisespecified, refer to sealing members composed of materials suitable tocreate and sustain a seal against the pressures associated with adownhole wellbore drilling environment.

The inner wall of first mandrel 28 may have a lower annular gland 70 tohouse a lower sealing member 72. The lower annular gland may be arounded groove, a square cut groove, an indentation etc. In theillustrated embodiment of FIG. 2B, the lower annular gland is squarecut. The lower sealing member may be an o-shaped sealing ring thatprotrudes from the lower annular gland so that the lower sealing membermay be compressed between the lower annular gland and the outsidesurface of the second mandrel creating therebetween a pressure and fluidseal to prevent fluidic communication between the wellbore and theannular hollow chamber.

In another embodiment of the present invention, flange 64 may includeports 82 to permit the bi-directional flow of fluids therethrough todecrease the likelihood of a pressure build up on either side of theflange. As one can appreciate, such a build up could create a pressurelock impairing the functionality of the agitation sub.

In one embodiment of the present invention, a dampener 74 may beinstalled to mitigate damaging contact between the sealing members. Thedampener, not shown, may be positioned between wall 48 and the flange.

In another embodiment of the present invention, there may be atransmission arrangement 76 between the first mandrel and the secondmandrel to permit the transmission of torsional forces there between.The transmission arrangement may, for example, be a tongue-and-groovearrangement. The transmission arrangement may include the lower sleevehaving one or more splines 78 that engage and axially move within one ormore receiving grooves 80 on the outer wall of second mandrel 30. Thesplines and grooves mate so that rotation of one part is transferred tothe other part. Of course, the one or more splines may be included onthe outer wall of second mandrel and the one or more receiving groovesmay be on the inner surface of the lower sleeve.

In one embodiment, the mandrels may each be constructed of one piece. Inanother embodiment, the mandrels may each be constructed of two or morecomponents. For example, as shown in FIG. 2A, the first mandrel may beconstructed of three primary components, including: an outer sleeve 40forming walls 32, 34, inner sleeve 42 and a lower sleeve 44 formingledge 50. The primary components of the first mandrel may define thelateral walls of the annular hollow chamber. For example, lower sleeve44 may threadedly connect with outer sleeve 40 proximal its lower end.The inner wall of outer sleeve 40, above the connection point with lowersleeve 44, may define an inner wall 34 open to the annular hollowchamber. The inner sleeve may threadedly connect to outer sleeve 40,below the tubular connection and above the end wall. The outer wall ofthe inner sleeve may extend below the end wall to define an inner walland of the annular hollow chamber.

In operation, the apparatus can be placed in a string and positioneddownhole. The apparatus may be connected in-line with a wellbore stringso that the position of second mandrel in the first mandrel is dependentupon weight on the string; applying torsional and axial forces on thestring to position the first mandrel and the second mandrel in the fullycompressed position; pump fluids through the string to develop a fluidpressure overcoming the weight on bit holding the first mandrel and thesecond mandrel in a sealing position and driving the first mandrel andthe second mandrel apart; allowing the pressure to dissipate when thefirst mandrel moves out of sealing position with the second mandrel suchthat the first mandrel returns back to a sealing position against thesecond mandrel; and continuing to pump fluids through the string tocreate an agitation effect of the first mandrel and the second mandrelbeing pumped apart and then returned to a sealing position

For example, when the string is urged down against the bottom or againstfrictional forces below the apparatus, herein called weight on bit, theapparatus is driven to axially compress, which causes the sealingmembers to come together (FIG. 2B). When fluid is pumped through thestring, it is stopped by the seal formed by the seated sealing parts andparts 52, 58 can only be forced apart when sufficient pressure builds upin bore 26 a The force must be sufficient to lift mandrel 28 off mandrel30.

When the pressure builds, the parts will be forced apart, causingmandrels 28, 30 to move into their axially extended position. Then, whenthe pressure dissipates by passage through bore 26 b, the weight of thestring causes the sealing parts to come back to together (FIG. 2B) untilpressure forces them apart again (FIG. 2A). Thus, the effect is aregular hammering and agitation in the string as the parts cycle:pressure forces the parts apart and then they come back together.

In the sealing position, the profile of the second sealing part may seatin and create a fluidic seal with the profile of the first sealing part,as shown in FIG. 2B, and thereby prevent the flow of fluids therethrough (except for any small flow through port 63). The fluidic sealmay be created by the profile of the second sealing part blockingcentral aperture 53 of the first sealing part, which prevents the flowof fluids through the central bore of the tubular body.

The fluidic seal may prevent any fluid communication across the firstsealing part so that, for example, drilling fluids being pumped fromsurface down the central bore of the string will no longer communicatebelow the fluidic seal provided by parts 52, 58. The effect of creatingsuch a fluidic seal, while drilling fluid continues to be pumped fromsurface, is agitation and hammering in the string.

If the apparatus is positioned between the drill bit and the drillcollar, driving the first mandrel and the second mandrel apart includeslifting a drill collar upwardly (i.e. toward surface) away from thedrill bit. Thus, the agitation and hammering can be applied very closeand perhaps directly at the drill bit.

The first and second mandrel may be arranged so that torsional forcesare transmitted between the two mandrels. For example, the lower sleevemay have one or more splines that engage and axially move within one ormore receiving grooves on the outer wall of second mandrel that matewith the one or more splines, or vice versa, the one or more splines maybe included on the outer wall of second mandrel and the one or morereceiving grooves may be on the inner surface of the lower sleeve.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to those embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein, but is to beaccorded the full scope consistent with the claims, wherein reference toan element in the singular, such as by use of the article “a” or “an” isnot intended to mean “one and only one” unless specifically so stated,but rather “one or more”. All structural and functional equivalents tothe elements of the various embodiments described throughout thedisclosure that are known or later come to be known to those of ordinaryskill in the art are intended to be encompassed by the elements of theclaims. Moreover, nothing disclosed herein is intended to be dedicatedto the public regardless of whether such disclosure is explicitlyrecited in the claims. No claim element is to be construed under theprovisions of 35 USC 112, sixth paragraph, unless the element isexpressly recited using the phrase “means for” or “step for”.

1. An apparatus comprising: a tubular body for connection within astring including a first mandrel and a second mandrel, and a centralbore defining a longitudinal axis of the tubular body and creating aflow path permitting a flow of fluids between the two mandrels andthrough the tubular body, the second mandrel secured, at leastpartially, within an annular bore of the first mandrel so that thesecond mandrel is telescopically arranged with and axially moveablewithin the first mandrel between a telescopically extended position anda compressed position; and a first sealing part and a second sealingpart, one of the first and the second sealing part being secured to thefirst mandrel and the other sealing part being secured to the secondmandrel, both sealing parts being within the fluid flow path of thetubular body, the first sealing part and the second sealing part beingpositioned to come together when the first mandrel and the secondmandrel are in the compressed position to form a seal in the fluid path,the seal substantially preventing the flow of fluids through the tubularbody.
 2. The apparatus of claim 1 further comprising a biasing memberacting between the first mandrel and the second mandrel and biasing thefirst mandrel and the second mandrel toward the compressed position. 3.The apparatus of claim 1 further comprising a transmission arrangementbetween the first mandrel and the second mandrel to transmit torsionalforces therebetween.
 4. The apparatus of claim 1 further comprising adampener to act between the first mandrel and the second mandrel in thecompressed position to mitigate damaging contact between the firstsealing part and the second sealing part.
 5. The apparatus of claim 1wherein the first sealing part has an aperture therethrough forming aportion of the fluid flow path and the second sealing part includes aprofile portion that seats in and plugs the center aperture when thefirst sealing part and the second sealing part come together to form aseal.
 6. A drill string comprising: a string of tubulars; a drill bitconnected at a distal end of the string of tubulars; a drill collar; anda hydraulically driven agitator positioned between the drill bit and thedrill collar.
 7. The drill string of claim 6 wherein the hydraulicallydriven agitator includes: a tubular body including a first mandrelconnected at an upper end directly or indirectly to the drill collar anda second mandrel connected at a lower end directly or indirectly to thedrill bit, and a central bore defining a longitudinal axis of thetubular body and creating a flow path permitting a flow of fluidsbetween the two mandrels and through the tubular body, the secondmandrel secured, at least partially, within an annular bore of the firstmandrel so that the second mandrel is telescopically arranged with andaxially moveable within the first mandrel between a telescopicallyextended position and a compressed position; and a first sealing partand a second sealing part, one of the first and the second sealing partbeing secured to the first mandrel and the other sealing part beingsecured to the second mandrel, both sealing parts being within the fluidflow path of the tubular body, the first sealing part and the secondsealing part being positioned to come together when the first mandreland the second mandrel are in the compressed position to form a seal inthe fluid path, the seal substantially preventing the flow of fluidsthrough the tubular body.
 8. The drill string of claim 7 wherein thehydraulically driven agitator further comprises a biasing member actingbetween the first mandrel and the second mandrel and biasing the firstmandrel and the second mandrel toward the compressed position.
 9. Thedrill string of claim 7 wherein the hydraulically driven agitatorfurther comprises a transmission arrangement between the first mandreland the second mandrel to transmit torsional forces therebetween. 10.The drill string of claim 7 wherein the hydraulically driven agitatorfurther comprises a dampener to act between the first mandrel and thesecond mandrel in the compressed position to mitigate damaging contactbetween the first sealing part and the second sealing part.
 11. Thedrill string of claim 7 wherein the first sealing part has an aperturetherethrough forming a portion of the fluid flow path and the secondsealing part includes a profile portion that seats in and plugs thecenter aperture when the first sealing part and the second sealing partcome together to form a seal.
 12. A method for creating an agitationeffect in a wellstring, the method comprising: connecting an apparatusaccording to claim 1 in-line with a wellbore string to position thesecond mandrel and the first mandrel in the compressed position whenthere is weight on bit in the wellbore string; applying weight on bit toposition the first mandrel and the second mandrel in the fullycompressed position; pumping fluids through the wellbore string todevelop a fluid pressure overcoming the weight on bit holding the firstmandrel and the second mandrel in compressed position and driving thefirst mandrel and the second mandrel apart; allowing the pressure todissipate such that the first mandrel and the second mandrel return backto the compressed position; and continuing to pump fluids through thewellbore string to create an agitation effect as the first mandrel andthe second mandrel continue to be pumped apart and then returned to thecompressed position.
 13. The method of claim 12 further comprisingapplying torsional forces through the wellbore string and transmittingthe torsional forces through the apparatus.
 14. The method of claim 12wherein driving the first mandrel and the second mandrel apart includeslifting a drill collar upwardly away from a drill bit.